Loading docks for trucks usually have an elevated dock floor surface approximately at the height of the average truck deck above the roadway surface. Trucks slowly back up to the dock at engage rubber bumpers on the dock to get as close as possible to the dock. Workers on the dock assist positioning on the truck with signals or red/green lights for example. Ramps, bridges or mechanical dock levelers are then positioned to bridge between the dock floor surface and the truck deck surface to enable wheeled vehicles to load and unload the truck.
The operation of wheeled vehicles such as fork lift trucks over such dock levelers exposes the operators to the risk of driving off the dock and plunging down with the forklift truck when the truck moves away from the dock. The truck may move due to failure of the brakes, sliding of the truck tires on the road surface, vibration causing slow gradual creeping movement caused by the forklift movements or driver error in driving away from the dock unexpectedly. Workers standing on the truck may also fall over due to such unintended movements of the truck. Air ride shock absorbers on the truck trailer may also cause unintended movements when the forklift bounces the truck bed and results in gradual movements away from the dock. For these reasons, safety regulations require some form of truck restraint to these prevent dangerous conditions from occurring due to movement of the truck.
To restrain movement of the truck relative to the dock, a common safety practice is to put chocks under the truck wheels. However wheel chocks alone are seldom adequate since slippery road surfaces can result in truck trailer movement. A more secure method is to mount a restraint device to the ground or wall surface adjacent the dock that engages the ICC bar of the truck or trailer. The ICC bar is a rear impact or under-ride guard that is mandated by government regulations and is common to large trucks usually in the form of two downward posts extending from the longitudinal truck chassis beams that support a horizontal beam known as an ICC bar. Of course if the ICC bar is broken, bent or damaged, wheel chocks may be used, however in a majority of cases properly functioning ICC bars can be used to secure the truck to the dock. The restraint device can be separate from the dock leveler device or combined together in a single unit. Restraint device may be mounted to the vertical wall of the loading dock or may be recessed into the roadway surface to extend upwardly to engage the ICC bar.
Conventional truck restraint devices engage the ICC bar with a hook or a stiff vertical bar. Truck beds are supported on the rear wheels with shock absorbers, metal springs or air ride shock absorbers. The movement of the forklift trucks when loaded can compress the truck suspension and cause difficulties in restraining the truck using the ICC bar which is usually about 2-4 inches thick. Therefore vertical movement of the truck suspension may cause disengagement of the truck restraint during loading and unloading.
Further, since the ICC bar is beneath the truck rear edge and dock workers are usually on the dock level above, visibility is limited to determine whether the ICC bar has actually been engaged properly or not. A worker would have to go to the ground level and look under the rear of the truck to visually inspect the restraint connection on the ICC bar. This is impractical especially in winter weather conditions, or in the dark and exposes the worker to several safety hazards walking on the roadway surface around moving trucks where drivers have limited visibility also. Closed circuit cameras may be used but are prone to impact damage in the loading dock environment.
Features that distinguish the present invention from the background art will be apparent from review of the disclosure, drawings and description of the invention presented below.